Environmental pollution and remediation: challenges and management of oil Spillage in the Nigerian coastal areas
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AMERICAN JOURNAL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
© 2011, Science Huβ, http://www.scihub.org/AJSIR
ISSN: 2153-649X doi:10.5251/ajsir.2011.2.6.834.845
Environmental pollution and remediation: challenges and management of
oil Spillage in the Nigerian coastal areas
Adelana S.O1, Adeosun.T.A2, Adesina A.O1 and Ojuroye M.O3
1
Department of Mechanical Engineering,Yaba College of Technology,Lagos,Nigeria
2
Department of Mathematics, Yaba College of Technology,Lagos,Nigeria
3
Lano Mechano &Associates,IKT.,Lagos,Nigeria
ABSTRACT
This paper examines the environmental pollution and remediation of oil spillage in the Nigerian
Coastal areas. Oil spillage is one of the greatest environmental problem Nigeria is currently
battling with especially in the Niger Delta zone. Oil communities have been at the receiving end of
this environmental problem. The problems has generated a lot of concern within of the three tiers
of government especially in oil producing states. The coastal area of the Niger Delta is the home
to oil explorations and exploitations in Nigeria. Oil spill incidents are common along the Nigeria.
The main sources of oil spill on the Niger Delta are: vandalisation of the oil pipelines by the local
inhabitants; ageing of the pipelines; oil blow outs from the flow stations; cleaning of oil tankers on
the high sea and disposal of used oil into the drains by the road side mechanics. By far the most
serious source of oil spill is through the vandalisation of pipelines either as a result of civil
disaffection with the political process or as a criminal activity.The paper also delves into the evil of
oil spillage facing the Nigeria environment. The Causes, Consequences, Geographic Information
System for Managing Oil Spill Incidents and Control Mechanisms were articulated to ameliorate
this problem and assist oil communities.
Keywords:Environment,spillage,remediation,exploration,pollution,exploitation,pipelines,
advection,simulation,anticlinal,bioremediation, phytoremediation, biosurfactants.
INTRODUCTION the three tiers of government especially in oil
producing states.
Oil spillage is a release of a liquid petroleum
hydrocarbon into the environment due to human SOURCES OF OIL SPILLS
activity, and is a form of pollution. The term often
Oil spills may occur for numerous reasons such as
refers to marine oil spills, where oil is released into
equipment failure, disasters, deliberate acts, or
the ocean or coastal waters. Oil spills include
human error (Anderson and LaBelle, 2000). Figure 1
releases of crude oil from tankers, offshore platforms,
shows the percentage each subcategory has
drilling rigs and wells, as well as spills of refined
contributed to the total number of oil spills in Nigeria
petroleum products (such as gasoline, diesel) and
in the past five years (Shekwolo,2005). Crude oils are
their by-products, and heavier fuels used by large
exclusively natural products, most of which are
ships such as bunker fuel, or the spill of any oily
produced from artificial wells. Natural seepage of
white substance refuse or waste oil. Spills may take
crude oils occurs in various parts of the world, not
months or even years to clean up. Oil also enters the
only on land, but also on the seabed. Seeps emerge
marine environment from natural oil seeps. Public
through fractures in the crests of folds in rock
attention and regulation has tended to focus most
formations beneath the sea floor that contain oil and
sharply on seagoing oil tankers.
gas deposits.Oil and gas tend to rise and become
Oil spillage is one of the greatest environmental trapped in anticlinal folds in sub sea rock strata.
problem Nigeria is currently battling with especially in Seepage occurs through fracture zones where the
the Niger Delta zone. Oil communities have been at folds are truncated at the sea floor. Seeps may
the receiving end of this environmental problem. The emanate from a single point or as many as 3 x 104
problems has generated a lot of concerns within of individual seepage signals may be merged onto a
high resolution profile record (Clark et al., 2000).Am. J. Sci. Ind. Res., 2011, 2(6): 834-845
Table1:Potential sources of Oil Spills
POTENTIAL SOURCES OF OIL SPILLS
Sabotage/Bunkering 36%
Engineering 0.50%
Human Error 2%
Corrosion 36%
Equipment Failure 6%
Others 2.50%
Table 2:Graphical representation of :Potential sources of Oil Spills
Extent of the problem: The Department of million and 13 million barrels have been spilled in the
Petroleum Resources estimated 1.89 million barrels Niger Delta since 1958. One source even calculates
of petroleum were spilled into the Niger Delta that the total amount of petroleum in barrels spilled
between 1976 and 1996 out of a total of 2.4 million between 1960 and 1997 is upwards of 100 million
barrels spilled in 4,835 incidents.(approximately 220 barrels (16,000,000 m3).
thousand cubic metres).
Causes of oil spillage in Nigeria: Oil spills are a
The Nigerian National Petroleum Corporation places common event in Nigeria and occur due to a number
the quantity of petroleum jettisoned into the of causes, including: corrosion of pipelines and
environment yearly at 2,300 cubic metres with an tankers (accounting for 50% of all spills), sabotage
average of 300 individual spills annually. However, (36%), and oil production operations (6.5%), with 1%
because this amount does not take into account of the spills being accounted for by inadequate or
"minor" spills, the World Bank argues that the true non-functional production equipment. The largest
quantity of petroleum spilled into the environment contributor to the oil spill total, corrosion of pipes and
could be as much as ten times the officially claimed tanks, is the rupturing or leaking of production
amount. The largest individual spills include the infrastructures that are described as, "very old and
blowout of a Texaco offshore station which in 1980 lack regular inspection and maintenance". A reason
dumped an estimated 400,000 barrels (64,000 m3) of that corrosion accounts for such a high percentage of
crude oil into the Gulf of Guinea and Royal Dutch all spills is that as a result of the small size of the
Shell's Forcados Terminal tank failure which oilfields in the Niger Delta, there is an extensive
produced a spillage estimated at 580,000 barrels network of pipelines between the fields, as well as
(92,000 m3). In 2010 Baird reported that between 9 numerous small networks of flowlines—the narrow
835Am. J. Sci. Ind. Res., 2011, 2(6): 834-845
diameter pipes that carry oil from wellheads to operations in the Delta, the environment is growing
flowstations—allowing many opportunities for leaks. increasingly uninhabitable.
In onshore areas most pipelines and flowlines are
People in the affected areas complain about health
laid above ground. Pipelines, which have an estimate
issues including breathing problems and skin lesions;
life span of about fifteen years, are old and
many have lost basic human rights such as health,
susceptible to corrosion. Many of the pipelines are as
access to food, clean water, and an ability to work.
old as twenty to twenty-five years. Even Shell admits
that "most of the facilities were constructed between Loss of mangrove forests: Vegetation in the Niger
the 1960s and early 1980s to the then prevailing River Delta consists of extensive mangrove forests,
standards. SPDC [Shell Petroleum and Development brackish swamp forests, and rainforests. The large
Company] would not build them that way today.” expanses of mangrove forests are estimated to cover
Sabotage is performed primarily through what is approximately 5,000 to 8,580 km² of land.
known as "bunkering", whereby the saboteur Mangroves remain very important to the indigenous
attempts to tap the pipeline. In the process of people of Nigeria as well as to the various organisms
extraction sometimes the pipeline is damaged or that inhabit these ecosystems.
destroyed. Oil extracted in this manner can often be
sold. Human impact from poor land management upstream
coupled with the constant pollution of petroleum has
Sabotage and theft through oil siphoning has become caused five to ten percent of these mangrove forests
a major issue in the Niger River Delta states as well, to disappear. The volatile, quickly penetrating, and
contributing to further environmental degradation. viscous properties of petroleum have wiped out large
Damaged lines may go unnoticed for days, and repair areas of vegetation. When spills occur close to and
of the damaged pipes takes even longer. Oil within the drainage basin, the hydrologic force of both
siphoning has become a big business, with the stolen the river and tides force spilled petroleum to move up
oil quickly making its way onto the black market. into areas of vegetation.
While the popularity of selling stolen oil increases, the Mangrove forests are included in a highly complex
number of deaths are increasing. In late December trophic system. If oil directly affects any organism
2006 more than 200 people were killed in the Lagos within an ecosystem, it can indirectly affect a host of
region of Nigeria in an oil line explosion. Nigerian other organisms. These floral communities rely on
regulations of the oil industry are weak and rarely nutrient cycling, clean water, sunlight, and proper
enforced allowing, in essence, the industry to self- substrates. With ideal conditions they offer habitat
regulate. structure, and input of energy via photosynthesis to
the organisms they interact with. The effects of
Consequences of oil spillage in Nigeria: Oil
petroleum spills on mangroves are known to acidify
spillage has a major impact on the ecosystem into
the soils, halt cellular respiration, and starve roots of
which it is released. Immense tracts of the mangrove
vital oxygen.
forests, which are especially susceptible to oil (mainly
because it is stored in the soil and re-released An area of mangroves that has been destroyed by
annually during inundations), have been destroyed. petroleum may be susceptible to other problems.
An estimated 5 to 10% of Nigerian mangrove These areas may not be suitable for any native plant
ecosystems have been wiped out either by growth until bacteria and microorganisms can
settlement or oil. The rainforest which previously remediate the conditions. A particular species of
occupied some 7,400 km² of land has disappeared as mangrove, Rhizophora racemosa lives higher in the
well. delta system. As the soils supporting R. racemosa
become too toxic, a non-native invasive species of
Spills in populated areas often spread out over a
palm, Nypa fruticans, quickly colonizes the area. This
wide area, destroying crops and aquacultures
invasive species has a shallower root system that
through contamination of the groundwater and soils.
destabilizes the banks along the waterways, further
The consumption of dissolved oxygen by bacteria
impacting sediment distribution lower in the delta
feeding on the spilled hydrocarbons also contributes
system. N. fruticans also impedes navigation and
to the death of fish. In agricultural communities, often
decreases overall biodiversity. In places where N.
a year's supply of food can be destroyed
fruticans has invaded, communities are investigating
instantaneously. Because of the careless nature of oil
how the palm can be used by local people.
836Am. J. Sci. Ind. Res., 2011, 2(6): 834-845
The loss of mangrove forests is not only degrading temperature can be fatal to certain marine species.
life for plants and animals, but for humans as well. Trees and shrubs provide shade and habitat for
These systems are highly valued by the indigenous marine species, while reducing fluctuation in water
people living in the affected areas. Mangrove forests temperature.
have been a major source of wood for local people.
The Niger River is an important ecosystem that
They also are important to a variety of species vital to
needs to be protected, for it is home to 36 families
subsistence practices for local indigenous groups,
and nearly 250 species of fish, of which 20 are
who unfortunately see little to none of the economic
endemic, meaning they are found nowhere else on
benefits of petroleum. Mangroves also provide
Earth. With the loss of habitat and the climate getting
essential habitat for rare and endangered species like
warmer, every prevention of temperature increase is
the manatee and pygmy hippopotamus. Poor policy
necessary to maintain some of the marine
decisions regarding the allocation of petroleum
environments. Other than restoring habitat, pollution
revenue has caused political unrest in Nigeria. This
can also be reduced. Problems such as pesticides
clash among governing bodies, oil corporations, and
from agricultural fields could be reduced if a natural
the people of Nigeria has resulted in sabotage to
pesticide was used, or the fields were moved farther
petroleum pipelines, further exacerbating the threat to
away from the local waterways. Oil pollution can be
mangrove forests.
lowered as well; if spills were reduced then habitat
The future for mangrove forests and other floral and environmental impacts could be minimized. By
communities is not all negative. Local and outside limiting the devastation caused by disturbances to the
groups have provided funds and labor to remediate marine environment, such as pollution, overfishing,
and restore the destroyed mangrove swamps. The and habitat loss, the productivity and biodiversity of
federal government of Nigeria established the Niger the marine ecosystems would increase.
Delta Development Commission (NDDC) in 2000
Control and management of oil spillage
which aims to suppress the environmental and
ecological impacts petroleum has had in the region. Oil Spillage Disaster Management: The Federal
Governmental and nongovernmental organizations Government, oil companies and non-governmental
have also utilized technology to identify the source agencies have made severalefforts to manage oil
and movement of petroleum spill. spill disaster along our coastline. These efforts are
discussed in the following sections
Depletion of fish populations: The fishing industry
is an essential part of Nigeria’s sustainability because Nigerian Government Action: To reduce the rate of
it provides much needed protein and nutrients for oil incidents along the Nigerian Coast particularly as
people, but with the higher demand on fishing, fish a result of vandalisation, the Federal Government
populations are declining as they are being depleted through an act of the National Assembly created the
faster than they are able to restore their number.
Fishing needs to be limited along the Niger River and Niger Delta Development Commission (NDDC). Part
of the responsibilities of the Commission is to
aquacultures should be created to provide for the
growing demand on the fishing industry. Aquaculture develop a master plan for the development of the
allows for fish to be farmed for production and Niger Delta, provide infrastructure and create an
enabling environment for industrialisation and
provide more jobs for the local people of Nigeria.
employment. There are also several other laws
Overfishing is not the only impact on marine dealing with issues related to oil pollution in the
communities. Climate change, habitat loss, and environment. Furthermore, standards for the
pollution are all added pressures to these important development of the environmental sensitivity index
ecosystems. The banks of the Niger River are maps for the coast of Nigeria have been developed
desirable and ideal locations for people to settle. The by the Environmental Systems Research Institute
river provides water for drinking, bathing, cleaning, (ESRI). These standards are to be used by all the oil
and fishing for both the dinner table and trading to companies to prepare ESI maps for their areas of
make a profit. As the people have settled along the operations in Nigeria.
shores of the rivers and coasts, marine and terrestrial
habitats are being lost and ecosystems are being A number of Federal and state agencies deal with the
drastically changed. The shoreline along the Niger problems of oil spill in Nigeria. The agencies include:
the Department of Petroleum Resources (DPR), the
River is important in maintaining the temperature of
the water because the slightest change in water
837Am. J. Sci. Ind. Res., 2011, 2(6): 834-845
Federal Ministry of Environment, the State Ministries removed by natural means through the process of
of Environment and the National Maritime Authority. evaporation, photochemical oxidation and
dispersions (Wardley-Smith, 1977). Bioremediation
A National Oil Spill Detection and Response Agency
can also be used for managing oil spill problems
(NOSDRA) has been formed and approved by the
(Hoff, 1993; Prince, 1993; Atlas, 1995). In addition,
Federal Executive Council of Nigeria. The Ministry of
apart from the mechanical and chemical oil spill
environment, which initiated the Agency, has also
cleaning methods that have been used in managing
forwarded to the federal executive council for
oil spill problems, oil spill models have on several
approval, the reviewed draft National Oil Spill
occasions being used to manage oil spills on the
Contingency Plan (NOSCP) which the Agency would
Nigerian Coast (Nwilo & Badejo, 2005).
manage (Alexandra Gas and Oil Connections, 2006).
Nigerian Sat 1: The Nigerian Sat 1 Satellite has
The establishment of the contingency plan and the
joined the Disaster Monitoring Constellation, an
agency was in compliance with the International
international early-warning satellite network
Convention on Oil Pollution Preparedness, Response
transmitting real-time information about droughts,
and Cooperation (OPRC90) to which Nigeria is a
earthquakes, deforestation and man-made disasters
signatory. According to the ministry's sources, the
observable from space. The Nigeria Sat-1, an Orbit
draft bill on the NOSDRA was being put together and
Satellite for geographical mapping, would also help to
would be forwarded to the National Assembly to be
check the perennial problem of oil pipeline
enacted into law (Alexandra Gas and Oil
vandalisation, and assist in combating and managing
Connections, 2006).Apart from intensifying efforts
oil spill incidents. The Nigeria Sat-1, would help in
towards compliance monitoring and enforcement of
monitoring oil spill by providing the spill position
oil and gas regulations and standards, the ministry is
which would serve as input data into the oil spill
also mounting pressure on the oil and gas operators
model. It would also give the extent of coastal water
for a gas flare-out. Effort is also being made,
andcoastal areas polluted. These information are vital
according to the sources, to ensure the use of
for quick clean up of oil impacted areas.
environmental-friendly drilling fluid and mud systems
(Alexandra Gas and Oil Connections, 2006) International Co-operation: Cracking down on
smugglers has proved difficult. To shore up the fight
There is a need to create serious awareness among
against oil smugglers in Nigeria, the US has donated
the populace on the implications of oil spill incidents
three 56 metre (180ft) refitted World War two-era
on the environment. Governments must assist the
patrol oats to the navy. United Nations has also said
rural communities in claiming their rights on oil spills
that United States would donate additional four
and ensure that digital ESI maps are readily available
vessels. The Pentagon is funding each boat’s
for managing oil spill maps. Government should have
refurbishment to the tune of $3.5m. The efforts of the
strict rules for local oil tankers that would ply our
Federal Government with the assistance of the US
coastal and inland waters as a result of the new
are already yielding fruits. The Nigerian Navy has
cabotage law that is just being passed into law in the
intercepted several tankers.
country (Nwilo & Badejo, 2005).
Geographic Information System for Managing Oil
Efforts of the Oil Companies and Non
Spill Incidents: A successful combating operation to
Governmental Agencies: Due to increasing
a marine oil spill is dependent on a rapid response
awareness in preventing and controlling spills in
from the time the oil spill is reported until it has been
Nigeria, the Clean Nigeria Associates (C.N.A.) was
fully combated. In order to reduce the response time
formed in November 1981. The C.N.A. is a
and qualify the decision-making process, application
consortium of eleven oil companies operating in
of Geographic Information Systems (GIS) as an
Nigeria, including N.N.P.C. The primary purpose of
operational tool has been suggested. Information on
establishing the C.N.A is to maintain a capability to
the exact position and size of the oil spill can be
combat spills of liquid hydrocarbons or pollutants in
plotted on maps in GIS and a priority of the combat
general (Nwilo & Badejo, 2005).
efforts and means according to the identified coastal
sensitive areas can be carried out.
Oil spillage can also be treated or removed by natural GIS offers opportunities for integration of oil drift
means, mechanical systems, absorbents, burning, forecast models (prediction of wind and current
gelling, sinking and dispersion. Oil spillage can be influence on the oil spill) in the computer program
838Am. J. Sci. Ind. Res., 2011, 2(6): 834-845
framework (Milaka,1995). Required information for oil angle. The deflection angle of the wind drift current
spill sensitivity mapping can be depicted on a set of depends on latitude (Buranapratheprat
thematic maps using GIS even though they can in andTanjaaitrong, 2000).
theory be depicted onto a single sheet. With the use
Eulerian Surface Waves Drift: Sobey and Barker
of a GIS, however, all the relevant information or (1996) gave reliable estimates of surface kinematics.
themes can be stored in the system and produced Higher order theory for stokes waves predicts that the
onto maps in a format that befits the needs of the water particle subject to uniform periodic waves will
day. Alternatively, modeling exercises using the GIS be transported in the direction of the wave advance.
can be conducted to assess the adequacy of any Since the water particle speed (u) given by stokes is
given oil spill contingency plan (Parthiphan, 1994). the same as the horizontal water particle speed (u),
stokes water particle speed was integrated into the
The creation of regional spill response centres along
Eulerian surface wave drift velocity equation given by
coastlines will help in managing oil spill problems
Sobey and Barker (1996) to get the speed of the
(Smith and Loza, 1994). The centres will use oil spill
Eulerian surface wave.
models for combating oil spill problems. Using data
collected with an airborne system to input one or Tides: The tidal amplitude and phase for this work is
several new starting point(s) into the model, will based on the results of Schwiderski’s global ocean
improve the accuracy of the further predictions tidal model and contained in Splaudling et al (1987).
(Sandberg, 1996). The tidal amplitudes and tides were input data into
the equations for the speed of tide given by Nelkon
New oil spill model (NOSM): NOSM simulates the
and Parker (1982). In a tide wave the horizontal
shoreline deposition through an exponential decay
motion, i.e. the particle velocity, is called the tidal
function. The movement of oil slick in the model
stream. The vertical tide is said to rise and fall, and
actually represents the movement of the centroid of
the tidal stream is said to flood and ebb. If the tide is
the slick.
progressive, the flood direction is that of the wave
The new oil spill trajectory mathematical model
propagation. If the tide is a standing wave, the flood
capable of simulating oil transport along our coastal
direction is inland or toward the coast (Canadian
waters came to limelight.. In developing this new
Hydrographic Service, 2005).
mathematical model, the major factors responsible
for transporting and advecting oil on water was Ocean Currents: The ocean currents affecting the
considered . The assumption made in the work was Nigerian coastal area include the following:
that oil will not mix with water, and that the density of (a.) Surface eastward flowing Guinea Current.
oil spill is less than that of water, thus the oil spill will (b.) Subsurface westward and northward flowing
move on water and not sink. The work is also limited Benguela Current.
to oil spill on open coastal water or deep sea. No (c.) Easterly flowing surface North Equatorial Counter
attempt to model the movement of oil spill on land or Current.
on swamps. Reddy and Brunnet (1997) gave the ocean current
responsible for moving oil as 100 percent of the
Advection is the main mechanism that governs the
speed of the ocean current. During the wet season,
transportation of suspended and surface oil slick. The
the Guinea Current and the Easterly Flowing North
combined effects of the following factors advect oil on
Equatorial Counter Current are responsible for
water:
moving oil spill. The Guinea Current has speeds of
1. Wind drift current 30cms-1 and touches the sea bed at depths
2. Waves shallower than 50m. From time to time, the Guinea
3. Tides Current reverses it's easternly flow. The reversal is
4. Ocean Current believed to be due to effects of the Benguela Current.
5. Longshore Current The mean eastward velocity for the NECC is 15 cm
The advection factors used in the model are s-1.This increases to speeds of more than 30 cm s-1
described in the following subsections. in the Guinea Current (Arnault, 1987). The greatest
flow for the NECC occurs in the boreal summer with
Wind Drift Current: The equation for the wind drift eastward speeds of up to 29 cms-1, which are
current is based on hyberbolic equations given by reduced during the spring. There is a reversal of a
Officer (1976). The direction of the wind drift current
majority of the current's flowin the western part of the
is the sum of the wind direction and a deflection
839Am. J. Sci. Ind. Res., 2011, 2(6): 834-845 basin during the early months of the year (Arnault, directions along the Nigerian Coastline were 1987). specified by Dublin Green et al (1997). During the Dry season, the Benguela current moves These directions are: the oil spill. Shannon (1985) gathered all available i. The west-east littoral drift along the western information about surface speed from previous coastline. studies and calculated the mean speed of the ii. The littoral drift off the north western flank of the Benguela Current to be 17 cm s-1. (Wedepohl et al. Niger Delta. 2000) found that the mean speeds of the current vary iii. The west-east littoral drift between Akasa point from
Am. J. Sci. Ind. Res., 2011, 2(6): 834-845
SWDC = Speed of wind drift current We have to vary the amplitudes and phases of tides
θWDC = Direction of wind drift current along the coastal waters.The simulated oil spill points
SSWD = Speed of Eulerian surface wave drift current for all the four phases for the wet season were
θSWD = Direction of Eulerian surface wave drift plotted in Map Info GIS software which is linked with
current the model in Visual Basic environment. The Oil Spill
STIDE = Speed of tide Trajectory for the wet season is shown in Figure 3.1
θTIDE = Direction of tide. below.The result of the simulation for wet season
SOC = Speed of ocean current. shows that the oil spill moves slower in deep sea and
θOC = Direction of ocean current. faster between the distance of 10km to 20km from
SLC = Speed of longshore current the shoreline. The reason for this is that in the deep
θLC = Direction of longshore current sea, there is no tidal effect while the tidal effect is
In addition to the new model developed, we also prevalent in the 10km to 20km region. Also, the net
looked into existing equations governing the fate of effect of the longshore current and tides increased
oil on water. We incorporated equations for the rate the speed of the oil spill near the shoreline.Tides and
of spreading and evaporation of oil spill on water to ocean currents are the major factors responsible for
our model. These equations are the most important oil spill movement along our coastline during the wet
factors in the determination of the fate of oil spill. season. For the study location above, the magnitude
Fay’s (1971) spreading theory is used in the model. of effective current velocity and directions remained
In the model, oil spill is assumed to spread radially the same throughout the four phases. The
under steady gravity and viscous forces, thus Fay’s magnitudes of these are .223m/s and 90o
radial spreading formula for gravity and inertial forces respectively.
is used. The formula developed by Mackay (1980) is
used to calculate the evaporate rate of oil in the Wind drift current and waves are secondary factors
model. The new trajectory model and the existing fate for moving oil spill during the wet season. The wind
model was written in the Visual Basic Environment drift current remained constant for the four phases.
(Windows based). This was done so as to make the The wind drift current is 1.94% of the wind speed in
model user friendly, by making use of its powerful deep water, 0.81% of wind speed in shallow water.
graphical user interface. Programming in the visual The wind drift velocity tends to zero along the
basic environment also enables us to link the model oastline. The wave velocity increases as one moves
with a base map of the Nigerian coastal areas in a towards the shoreline. The magnitude of the wave
MapInfo GIS environment. velocity is lower than that of the wind drift in the first
three phases, but higher than that of the wind drift
Study Area and Hypothetical Simulations of Oil current in the fourth phase. The effect of waves is
Spill Position with the Model: An hypothetical spill negligible in deep sea (1000m+) but cannot be
site around OPL 250 located about 150km off the dispensed within shallow sea or near the coastline.
Nigerian coastline was chosen as the study area. The
actual spill position is longitude 4o 30’ 46.20” E and The simulated oil spill for wet season reached the
latitude 4o 25’39.80” N and were made for wet and shore (around Penington River) after 104hours(about
dry seasons for the study area above. The 4.5 days). The oil spill will continue to move along the
simulations for the wet and dry seasons were done in shoreline towards Escravos (i.e. in the direction of the
four phases for each season. For phase one, longshore current). When the tide is high, the oil spill
simulations were made from the spill point up to a will move into the coastal lands and negatively impact
point around the 100m isobath. In phase two, the ecosystem.By the end of the 104 hours a total of
simulations were made from the point around the 94,525.660barrels of oil would have evaporated. This
100m isobath to a point about 20km to the coastline. amount represents 16.88% of the 560,000 barrels of
Simulations for phase three were made from the oil spilt. In addition the Slick area at the end of the
point about 20km to the coastline up to another point 104hours would be 1782.058km2. The simulated oil
about 10km to the coastline. Simulations for the last spill points for all the four phases for the dry season
phase were made from the point about 10km to the were plotted in MapInfo GIS software which is linked
coastline up to the coastline. The reason for making with the model in Visual Basic environment. The Oil
the simulations in four phases is that the effect of Spill,Trajectory for the dry season is shown in Figure
tides is negligible for the deep sea, while the tidal 3.0 below.
effect increases as one moves closer to the coastline.
841Am. J. Sci. Ind. Res., 2011, 2(6): 834-845
Fig 2.0: Oil Spill Trajectory for the Wet Season
Fig:3.0: The Oil Spill,Trajectory for the dry season
842Am. J. Sci. Ind. Res., 2011, 2(6): 834-845
The result of the simulation for dry season shows that species to clean up spills. The first stage of cleanup
the oil spill moves also moves slower in deep sea involves Hibiscus cannabinus, a plant species
and faster between the distance of 10km to 20km indigenous to West Africa. H. cannabinus is an
from the shore line during the dry season. The annual herbaceous plant originally used for pulp
reason for this is that in the deep sea, there is no tidal production. This species has high rates of
effect while the tidal effect is prevailent in the 10km to absorbency and can be laid down on top of the water
20km boundary. Also, the net effect of the longshore to absorb oil. The oil saturated plant material is then
current and tides increased the speed of the oil spill removed and sent to a safe location where the
near the shoreline. Tides and ocean currents are also hydrocarbons can be broken down and detoxified by
the major factors responsible for oil spill movement microorganisms. The second stage of bioremediation
along our coastline during the dry season. For the involves a plant known as Vetiveria zizanioides, a
study location above, the magnitude of effective perennial grass species. V. zizanioides has a deep
current velocity and directions remained the same fibrous root network that can both tolerate chemicals
throughout the four phases. The magnitudes of these in the soil and can also detoxify soils through time
are .17m/s and 0o respectively. Oil spill moves requiring little maintenance. The people of Ogbogu
slower during the dry season. The reason for this is hope to use these methods of bioremediation to
that the magnitude of the ocean current is lesser improve the quality of drinking water, soil conditions,
during the dry season. Wind drift current and waves and the health of their surrounding environment.
are also secondary factors for moving oil spill during
Within the Imo State of Nigeria, a study was
the dry season. The wind drift current remained
conducted in the city of Egbema to determine the
constant for the four phases. The wind drift current is
microfloral communities present at the site of an oil
spill. These microorganisms have the ability to break
about 2.% of the wind speed during the dry season.
down the oil, decreasing the toxic conditions. This is
The wave velocity increases as one moves towards
recognized as another method of bioremediation and
the shoreline. The magnitude of the wave velocity is
scientists are trying to determine whether the
lower than that of the wind drift in the first three
properties these microorganisms possess can be
phases, but higher than that of the wind drift current
utilized for the cleanup of future spills.[23]
in the fourth phase. The effect of waves is negligible
in deep sea (1000m+) but cannot be dispensed with However bleak this situation may seem for the Niger
in shallow sea or near the coastline . Delta region there are clearly alternatives that can be
implemented to save it from future contamination.
The results from the model for dry season indicate Satellite imagery combined with the use of
that the oil spill reached the shore (at the entrance of Geographical Information Systems (GIS) can be put
Benin River) after 162hours (6.5days). The oil spill to work to quickly identify and track spilled oil. To
would then move towards Forcados (i.e. in the hasten the cleanup of spills, regional cleanup sites
direction of the longshore current) around where its along the problem areas could help contain spills
flow would be affected by the longshore current more quickly. To make these tasks feasible more
coming from Penington end. The oil spill would be funding must be provided by the stakeholders of the
stationary at this point, and move into the coastlands oil industry. Nongovernmental organizations will keep
during high waters.By the end of the 162 hours a total fighting the damaging effects of oil, but will not win
of 147241.894barrels of oil would have evaporated. the battle alone.
This amount represents 26.293% of the 560,000
barrels of oil spilt. In addition the slick area at the end Approaches to Bioremediation: The two main
of the 162hours would be 1628.440km2. approaches to oil spill bioremediation are
bioaugmentation and biostimulation.
Biological remediation: Bioaugmentation involves the use of beneficial
microbes that have an affinity towards a specific
The use of biological remediation has also been
pollutant. Typically, these microbes are suspended
implemented in areas of the delta to detoxify and
by a stabilizing agent and lie dormant until activated
restore ecosystems damaged by oil spills.
in solution and applied together with micro-nutrients
Bioremediation involves biological components in the
and stimulants. Bioaugmentation allows one to
remediation or cleanup of a specific site. A study
control the nature of the biomass. It ensures that the
conducted in Ogbogu located in one of the largest oil
proper team of microbes is present in the spilled soil
producing regions of Nigeria has utilized two plant
in sufficient type, number, and compatibility to attack
843Am. J. Sci. Ind. Res., 2011, 2(6): 834-845
the constituents effectively and break them into their nucleic acids of living organisms, and therefore
most basic compounds (Venosa et al., 1996;McKee should be adequately provided.
and Mendelssohn, 1995). Biostimulation on the other
CONCLUSION AND RECOMMENDATIONS :
hand involves aeration and the addition of selected
Oil spills are caused by human errors and
micronutrients and sometimes topsoil in appropriate
carelessness, but sometimes by natural disasters
quantities (Shekwolo, 2005; Swannell et al., 1999). It
such as hurricanes or earthquakes. Deliberate acts
is only effective when indigenous microbial
by terrorists, countries at war, sabotage and
populations, present in the substrate, are high
bunkering, or illegal dumpers however, prove that oil
enough to degrade the PHC, and when these
spills are not always accidents. Some oil from any
microbes can readily adapt to foreign
spill is degraded into simpler substances naturally by
substrates.Mishra et al. (2001) argued that since
microorganisms. Use of biosurfactants have been
microorganisms capable of degrading oil usually
shown to be of desirable characteristics, therefore it
grow at the expense of one or more components of
is one of the best approaches suitable for
crude oil, and these bacteria are ubiquitous, there is
emulsification of crude oil spills for biodegradation.
usually no reason to add PHC biodegraders unless
The biodegradation process is relatively slow, and
the indigenous bacteria are incapable of degrading
when an oil spill occurs, workers must act fast to
one or more important components. The size of the
protect the environment. Most crude oils are
hydrocarbon degrading bacteria population usually
inherently biodegradable, but they contain essentially
increases rapidly in response to oil
no nitrogen, phosphorous or other trace elements
contamination,and it is very difficult, if not impossible
that are necessary to stimulate the microbes that
to increase the microbial population over that which
degrade the oil.
can be achieved by biostimulation alone (Lin and
Mendelssohn, 1998). The carrying capacity of most
In the same vein,the Nigeria Sat-1, would help in
environments is probably determined by factors such
monitoring oil spill by providing the spill position
as predation by protozoan, the oil surface area, or
which would serve as input data into the oil spill
scouring of attached biomass by wind activity that are
model. It would also give the extent of coastal water
not affected by bioaugmentation, and added bacteria
and coastal areas polluted. These information are
seem to compete poorly with the indigenous
vital for quick clean up of oil impacted areas.
population. Therefore, it is unlikely that they will
persist in a contaminated soil even when they are
In order to reduce the response time and qualify the
added in high numbers. Hence, bioaugmentation may
decision-making process, application of Geographic
not have any long term beneficial effects in clean up
Information Systems (GIS) as an operational tool has
operations.Biostimulation involves the addition of
been suggested.
rate-limiting nutrients to accelerate degradation by
indigenous microbes.This assumes that every
Information on the exact position and size of the oil
organism needed to accomplish the desired
spill can be plotted on maps in GIS and a priority of
treatment-results is present (Mishra et al., 2001).
the combat efforts and means according to the
Though it is not certain that those organisms present
identified coastal sensitive areas can
are the most suitable to degrade the pollutant. When
be carried out.
an oil spill occurs, it results in a huge influx of carbon
The creation of regional spill response centres along
into the impacted environment. Supplying enough
coastlines would help in managing oil spill problems
nitrogennous nutrients to the cultures to enable their
(Smith and Loza, 1994). The centres will use oil spill
proliferation present serious problems, since sea,
models for combating oil spill problems. Using data
river, or lake water and soil have little nitrogen and
collected with an airborne system to input one or
phosphorus, rapid oil utilization will require external
several new starting point(s) into the model, will
supplies of these elements for the oil-consuming
improve the accuracy of the further predictions.
microorganisms. Carbon is the basic structural
component of living matter, and in order for the
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